Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, read DTCs
  Does the scan tool display this DTC as active?
  
  Yes
  - Go To 2
  No
  - Test complete. The condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals and correct pin tension.
  - Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
CHECK THE (W521) CLUSTER DIMMER SWITCH SENSE CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the VSIM C2 harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (W521) Cluster Dimmer Switch Sense circuit between ground and the VSIM C2 harness connector.
  Is there any voltage present?
  
  Yes
  - Using the wiring diagrams as a guide, repair the (W521) Cluster Dimmer Switch Sense circuit for a short to voltage.
  No
  - Replace the Vehicle System Interface Module (VSIM) in accordance with the Service Information. Refer to MODULE, VEHICLE SYSTEM INTERFACE, REMOVAL .
  - Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .